1. Field of the Invention
The present invention relates generally to integrated circuit chip package technology and, more particularly, to a package-in-package (PIP) semiconductor device which is configured to minimize the electrical interference between one internal semiconductor package and another internal semiconductor package or die from each other or from the surrounding environment, while minimizing the stack-up height of these internal electronic components. The configuration of the semiconductor device of the present invention also allows for ease in the testing thereof.
2. Description of the Related Art
Radio frequency (RF) shielding is required on certain semiconductor devices in order to minimize electro-magnetic interference (EMI) radiation from the semiconductor device. RF shielding is further sometimes required to prevent RF radiation from external sources from interfering with the operation of the semiconductor device.
RF shielding is generally accomplished in one of three ways. A first method is to attach a metal can over an electronic component such as a semiconductor package or a semiconductor die after such electronic component has been attached to an underlying support surface such as a printed circuit board. One alternative to the shield attach method is to embed an RF shield directly into a semiconductor package. In this embedded shield method, the RF shield (which is typically made of metal) is directly attached to the substrate of the semiconductor package through the use of solder or a conductive adhesive. The shield may be fully embedded within the mold compound of the finished semiconductor package, or can be exposed after assembly. Another method for facilitating RF shielding, often referred to as a conventional conformal shield, involves initially placing electronic components such as those described above on an underlying substrate or strip, and thereafter over-molding such substrate or strip in a manner defining individual mold caps thereon. These individual mold caps are oriented such that upwardly facing pads of the substrate or strip are exposed, i.e., not covered by the mold caps. A conductive coating is then applied to the substrate or strip such that it covers the units and also makes electrical contact to the upwardly facing pads. The substrate or strip is then singulated into individual units. Alternatively, the individual units may be singulated, thus exposing the metal layer(s) on the package edge, allowing the conformal coated shield to contact the exposed grounded metal.
In the electronics industry, there is also an increasing need for semiconductor devices of increased functional capacity, coupled with reduced size. This particular need is often being satisfied through the use of package-in-package (PIP) semiconductor devices. A typical PIP semiconductor device comprises various combinations of electronic components including passive devices, semiconductor dies, semiconductor packages, and/or other elements which are arranged in a horizontal direction, or stacked in a vertical direction on an underlying substrate. In many PIP devices, the substrate and the electronic components are interconnected to one another through the use of conductive wires alone or in combination with conductive bumps, with such electronic components thereafter being encapsulated by a suitable encapsulant material which hardens into a package body of the PIP device.
The present invention provides a unique combination of the above-described RF shielding and PIP technologies, and provides a PIP semiconductor device wherein an RF package and a die are stacked, with conformal shielding also being included to provide RF noise mitigation (i.e., minimize noise interference) between the RF package and the die (or any other component in the PIP device), or between the RF package and the external environment. These, as well as other features of the PIP device of the present invention, will be described in more detail below.